In 1994, it was discovered that a mutation of the gene found on chromosome 4 causes achondroplasia. It is known as the "fibroblast growth factor receptor-3" (FGFR3). The way in which mutations in FGFR3 cause achondroplasia are currently being researched.

Achondroplasia is considered to be a Dominantly Inhereted Disorder, which means the disorder is due to a dominant allele. A common misconception of dominant and recessive alleles is that dominant means it is dominant in the population, but this is false. A dominant allele means that it is fully expressed in the organism's appearance, whereas a recessive allele has no noticeable effect on the organism's appearance.

In general, a person can be a carrier of a disease and not show any symptoms, but that is not the same in the case of achondroplasia.

In over 80% of cases, achondroplasia is not inherited, but results from a new mutation that occurred.

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Opinions differ on the frequency of achondroplasia within the population. Varying sources estimate the risk to be between 1 in every 10,000 people to 1 in every 40,000 people.

Inheretence risks in achondroplasia: One parent with achondroplasia and one average statured spouse has a 50 percent chance of having a child with achondroplasia and 50 percent chance of having a child without achondroplasia.

If both parents have achondroplasia, the child has a three in four chance of having the disease.

A child with two dominant alleles has almost no chance of survival after the first year or life.

It is recommended that women with achondroplasia who become pregnant have very specialized prenatal care by an obstetrician. Prenatal diagnosis is often possible. The child must then be delivered by cesearian section.